Authors Year Title
Korn 1991 Threedimensionally preserved clymeniids from the Hangenberg Black Shale of Drewer (Cephalopoda, Ammonoidea; Devonian-Carboniferous boundary; Rhenish Massif).
Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1991, H.9: 553-563, fig.1-5; Stuttgart.
Korn 1993 The ammonoid faunal change near the Devonian-Carboniferous boundary.
Annales de la Societé géologique de Belgique, 115 (2): 581-593, fig.1-13; Bruxelles.